The lock and lift tool of the invention is designed to quickly engage a rectangular dovetailed socket, one that has a rectangular top open surface but which has two inclined interior surfaces if observed in a sectional elevation view. The dovetailed socket may be cut near the center of a heavy metal plate or, preferably, in a small metal plate which may be bolted or otherwise attached to any heavy object, such as an engine block, which is to be moved or lifted by a crane.
A form of lock and lift tool is disclosed in U.S. Pat. No. 4,575,144, issued March 1986 to the present inventor. That tool is a three-piece tool having two plates with inclined bottom surfaces and a third locking plate which is dropped between the two plates to force the two plates apart into the dovetailed socket. A lifting cable passing through aligned openings in the three plates effectively locks the tool into the dovetailed socket. The three-piece tool functions very well if dirt doesn't make installation of the third locking plate difficult or if the third locking plate isn't lost.
The present invention is for a two-piece lock and lift tool that includes a main frame that has an inclined bottom surface and a pivoting plate that abuts against the main frame and has an inclined bottom surface. The pivoting plate may pivot out from the main frame for quick and easy release from or attachment to a dovetailed socket unless it is locked to the main frame by some means that holds the pivoting plate to the main frame such as a cable under tension or a lifting hook passing through aligned openings in the locking member and main frame.
Briefly described, the invention is for a tool for connecting a crane hook or cable to a load by expanding two inclined surfaces of the tool into a dovetailed opening formed in the load, or to a small plate attached to the load. The tool is quickly attached or released by removing the hook and pivoting out the pivoting plate from the main frame.